Drivetrain New To Stangs, Need Help Diagnosing Aod Problem!

hey everyone, im Skyler, just picked up a 95 5.0 auto convertible with powerdyne supercharger for cheap because it needed a new transmission,my first mustang experience, it would go in reverse and not other gerars, did a quick burnout in reverse, stall converter gripped great. i picked up a rebuilt tranny and swapped it in. got it mostly together, started it up and had an awful metal scraping noise...flex plates weight was scraping the shroud ...transmission back off, new flexplate, put it all back together...scraping gone, but still wouldnt move &$^#@..., yes it is full on fluid. car came with a 2500 stall converter, new transmission came with new torque converter, i used the stall converter the car came with instead, positive it is on all the way, so im assuming that its bad.(btw first time putting it all back together forgot to add fluid to it after emptying it mostly outnever put it in gear with scraping sound and never ran it long, added a quart of fluid before installing it second time) but first start up of the day for past 3 days, the car will go into gear and drive for a short distance beautifully, then back to nothing. dropping the tranny again tomorrow maybe, but if anyone has ideas on other things i could check first it would be much appreciated! if not, 3rd times the charm!

Unfortunatly the tranny came mostly full fluid, i got it from a reputable parts guy and he said it was rebuilt and installed on a car for testing. I added a couple quarts and in park at cold temp the fluid shows up halfway on warm temp. You do test in park right?

once again, i start it up this morning, put it in drive, took off with no hesitation, drove around, held down brakes, took off again, put it in park, put it back into gear...then nothing, fluid absoluetly shows full on the stick